If t1 hours are required to travel d miles at v1 miles per hour and t2

Question

If t1 hours are required to travel d miles at v1 miles per hour and t2 hours are required to travel the same d miles at v2 miles per hour, is the overall average speed equal to (v1+v2)/2?

(1) t1 = t2 
(2) v1 = v2

Himanshu9818 · Accepted Answer

Ans D
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TIMEBBA · Answer

The Answer is C.I solved i the old traditional way.

Lastlap2016 · Answer

Avg speed= (D1 + d2 + d3 +....... Dn)/(t1+ t2+t3 +..... tn) = ( V1*t1 + V2*t2 + V3*t3 +.......... Sn*tn)/(t1+ t2+t3 +..... tn)

so now for given ques , avg speed= (V1*T1 + V2*T2)/T1+T2.............................. (1)

1st statement , t1=t2 ==> (1) gets reduced to avg speed = (V1+ V2)/2 Sufficient

2nd statement, v1=v2 ==> (1) GETS REDUCED TO avg speed = V1=V2 which is equal to (V1+V2)/2 since both are equal.

Hence Ans D

MathRevolution · Answer

There are 5 variables (v1, t1, v2, t2, d) and two equations (v1t1=d, v2d2=d) in the original condition. In order to match the number of variables to the number of equations, we need 3 equations. Therefore, there is high chance that E is the correct answer. Using both the condition 1) and the condition 2), we get the condition 1)=the condition 2). The answer is always yes and the conditions are sufficient. Hence, the correct answer is D.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

Deepashree3108 · Answer

Since it is mentioned that D1=D2, taking any of the T1=T2 or V1=V2 will equate the other dimension. Please correct me if I am wrong.
I think it should be Option D

Aboyhasnoname · Answer

Hi, Please Help....

t1, v1 and t2,v2 ..and d is same for both..Can't we just solve this..Like....(v1 + v2)/2....
So average speed will be possibel( v1 +v2.)/2 ..this would be possible when v1 and v2 are equal...Since D is equal

1. Says t1, t2 are equal..and d is equal so v1, v2 are equal
2. Says v1, v2 are equal.....

rak08 · Answer

Bunuel

we could have solved it just by saying
if time is equal for equal distance then speed has to be equal 
hence 1 suff.
 is this ok?

If t1 hours are required to travel d miles at v1 miles per hour and t2

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GMAT Data Sufficiency (DS) Questions

If t1 hours are required to travel d miles at v1 miles per hour and t2

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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